SEDONA, Ariz. — Authorities seeking answers to what caused two deaths and more than a dozen illnesses at an Arizona resort's sauna-like sweat lodge were investigating whether any of the victims had medical conditions or had been fasting.

In all, 21 of the 64 people crowded inside the sweat lodge Thursday evening received medical care at hospitals and a fire station. Four remained hospitalized Friday evening — one in critical condition and the others in fair condition.

Authorities identified the two people as James Shore, 40, of Milwaukee and Kirby Brown, 38, of Westtown, N.Y.

Authorities haven't determined the cause of the deaths and illnesses; tests for carbon monoxide and other contaminants were negative.

"It's not something you'd normally see at one of the resorts there, and it's unfortunate regardless of the cause," Yavapai County sheriff's spokesman Dwight D'Evelyn said.

Investigators were working to determine whether criminal actions might have been a factor in the incident, D'Evelyn said.

'Spiritual Warrior' retreatThe Angel Valley Retreat Center sits on 70 acres nestled in a scrub forest just outside Sedona, a resort town 115 miles north of Phoenix that draws many in the New Age spiritual movement.

Self-help expert and author James Arthur Ray rented the facility as part of his "Spiritual Warrior" retreat that began Oct. 3 and that promised to "absolutely change your life."

Ray spokesman Howard Bragman confirmed that his client was holding an event at the retreat, as he has done in the past. Authorities said Ray was inside the sweat lodge Thursday evening and was interviewed at the scene.

"We express our deepest condolences to those who lost friends and family, but we pray for a speedy recovery for those who took ill," Bragman said. "At this point there are more questions than answers, so it would not be appropriate to comment further."

Video: Retreat deaths
Sweat lodges, like that held on the final day of the Angel Valley retreat, are commonly used by American Indian tribes to cleanse the body and prepare for hunts, ceremonies and other events. The structure used Thursday was crudely built and covered with tarps and blankets.

Stones are heated up outside a lodge, brought inside and placed in a pail-sized hole. The door is closed, and water is poured on the stones, producing heat aimed at releasing toxins in the body.

The ritual in sweat lodges is helpful in restoring balance and changing people's attitudes and self-image, said Joseph Bruchac, author of "The Native American Sweat Lodge: History and Legends."

Cases of other deathsPeople have died in sweat lodges in the past. They were either sick tribal elders who voluntarily stayed until they died or people who had heart conditions and were in poor health.

"The sweat lodge needs to be respected," Bruchac said. "When you imitate someone's tradition and you don't know what you are doing, there's a danger of doing something very wrong."

A woman who answered the phone at the Angel Valley resort Friday said its founders, Michael and Amayra Hamilton, would have no comment. A call to the Hamiltons' home went unanswered.

The Angel Valley Spiritual Retreat Center, built on former ranch property in the high-desert and red-rock country of northern Arizona, bills itself as a natural environment for self discovery and healing through a holistic approach aimed at balancing the mind, emotions, body and spirit.

The property includes American Indian structures such as teepees, guest houses and outdoor labyrinths made of stones.

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